Many approaches are used to monitor landslides. The detection techniques vary depending on the distance between the area of interest (AOI) and receiving devices. In this paper, a technique for predicting and monitoring the landslides in steep areas in the foothills or mountain range, using wireless sensor networks, was introduced, analyzed and simulated. The proposed landslide monitoring system relies on placing an array of wireless sensor nodes as transmitters array, especially in the steep areas, and receiving and analyzing the signals received from the array by two synchronous wireless receiver nodes.In fact, the proposed system for monitoring the phenomenon "landslide" measures the changes of the phase difference between the two wireless sync receiver nodes, before and after the occurrence of landslides. In addition to the acceptable accuracy and reliability of the proposed monitoring system taken into consideration, it also has acceptable qualification for monitoring the slope foothills in limited areas under critical conditions.In this study, No fb01eld test was tried, but there is a complete simulation example to illustrate the technique using an array of six transmitters and two receivers. The accuracy of the results is carefully reviewed and placed on evaluation.In this paper, an inexpensive and low noise displacement change detection technique based on the phase difference between two coherently demodulated receiving signals is presented. It measures the phase difference of the range between the transmitter (or target) in the AOI and two wireless sync receiver nodes. The area of interest (AOI) refers to the surface area of a sloped hillside, and the receiving devices are at some distance away from the foothill. The transmitter array is either hardwired or programmed to transmit signals in a coordinated sequence. The two receivers are set apart at small distances and demodulate the receiving signals independently, yet coherently. It can detect the early landslide for small, but critical areas, with ranges up to 250 m when popular IEEE 802.11n family devices are used.

Wireless sensor networks have been used for monitoring of events and environment for a long time. The networks are used in numerous applications such as monitoring of battle fields, traffic, forest firing, tracking of an object and so on. Successful performance of WSNs depends on appropriate coverage of the environment. Coverage has a severe dependence on the infrastructure including the numbers and the places of sensors. So, a substantial step in designing networks is to specify the deployment strategy of nodes. Most of the deployment algorithms have been focused in minimizing network constraints and optimizing sensor coverage in recent years. The purpose of this study is to accommodate the physical form of environments in deployment problem which have not been investigated in previous works. Indeed our goal is to advantage from the ability of GIS in sensors deployment problems in order to make the problem closer to reality. As a result, the Minimax algorithm based on Voronoi diagram is used for optimizing sensor coverage in an urban and a natural area. This method resulted in 12 and 19 percent increase in sensor coverage respectively.